Analysts poured cold water on calls for voters to abandon their principles and vote for the strongest Unionist, non-Tory or anti-Brexit candidate, warning that only a handful of seats were close enough for tactical voting to have an impact. In the first week of the election campaign, most parties issued calls for voters to lend them their votes in order to keep out another candidate. Ruth Davidson said her party was the “best bet” to stop a second independence referendum, with her party’s only MP in Scotland, David Mundell, launching his campaign in marginal Dumfriesshire, Clydesdale and Tweeddale with the slogan “No to indyref2”. Scotland’s only Labour MP, Ian Murray, was reported to have appealed for the support of Liberal Democrat and Tory voters to hold off the SNP in his Edinburgh South seat, although he later clarified that he wanted people to vote Labour across Scotland. Mark Diffley, director of polling firm Ipsos Mori Scotland, said that while more polling data was needed, tactical voting may only be a factor in half a dozen SNP seats. In 38 of the 56 constituencies won by the SNP in 2015, the nationalist vote is larger than that of the Conservatives, Labour and the Liberal Democrats combined. Diffley said it would take “an extraordinary feat of organisation” to convince sufficient numbers of people to vote tactically in June. “It genuinely would be a surprise if they got 56 seats again, but at the moment there isn’t anything to suggest it will be less than 50,” he said. Ailsa Henderson, the head of politics at the University of Edinburgh, said: “Tactical voting only works if people really do have a sense of who the strongest challenger might be. “All parties are contending that’s them. In the absence of constituency level polling, it’s hard to tell who’s right.”